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Accumulated other comprehensive income (Detail) - USD ($) $ in Millions | 9 Months Ended
--- | ---
Sep. 30, 2025 | Sep. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | $ 649,368 |
Ending Balance | 698,155 |
Unrealized investment gains (losses) [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 117 | $ 190
Other comprehensive income | 99 | 81
Ending Balance | 216 | 271
Foreign currency translation [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | (7,039) | (5,393)
Other comprehensive income | 1,207 | 78
Ending Balance | (5,832) | (5,315)
Long duration insurance contracts [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 2,015 | 1,353
Other comprehensive income | (120) | (10)
Ending Balance | 1,895 | 1,343
Defined benefit pension plans [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 1,148 | (97)
Other comprehensive income | (102) | (44)
Ending Balance | 1,046 | (141)
Other AOCI transactions [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 175 | 184
Other comprehensive income | (23) | (34)
Ending Balance | 152 | 150
Accumulated other comprehensive income [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | (3,584) | (3,763)
Other comprehensive income | 1,061 | 71
Ending Balance | $ (2,523) | $ (3,692)

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